As might be expected, the art of horseshoe structure is a crowded art which includes several hundred patents granted over a period of more than one hundred years. Many of them reveal efforts to deal with the problems solved by the present invention, but without an adequate understanding of the precise anatomical relationships involved.
Wilkinson U.S. Pat. No. 61,974 discloses a shoe which is rounded on the lower surface, and has steel plates attached to the toe and heels thereof, which are the points of greatest wear. However, the disclosure reveals no awareness of the anatomical factors which are necessary to be considered in the shape and structure of an effective shoe.
Bryden U.S. Pat. No. 155,362 discloses a shoe which dispenses with caulks (which were evidently prevalent in shoes at that time) but which gives the same results as shoes with caulks. Some awareness is revealed of some of the effects of shoe structure upon the muscles and tendons of the animal, and the rolled front surface on the toe of this shoe is an effort to take into account those effects. However, it does not conform to the anatomical structure of the foot.
Read U.S. Pat. No. 196,479 discloses a shoe intended to deal with a specific ailment of horses ("contraction of the feet"). The bottom of this shoe is rounded, but this rounding is not related to the specific anatomical structure of the horse's foot.
Dellinger U.S. Pat. No. 570,278, discloses a shoe which is thinned along the inner margin of its upper surface. However, this thinning is not discussed, nor is any role for it but, from the description given of the shoe generally, it seems to be for the purposes of weight reduction. No awareness is revealed that this structure might have physiological effects on the functioning of the hoof. There is no other feature of this shoe which is relevant to the novelty of the present invention.
Several early patents disclose caulks for horseshoes to be applied at different points thereof, but these are for the purpose of providing traction on difficult surfaces. None of them discloses an insert of abrasion-resistant material to be embedded in the sole of the shoe at the points of greatest wear, or an application of such material to be applied to the same area on the surface of the sole of the shoe, or even an awareness that there is a desirable anatomical reason for the location of a wear-resistant area at those points:
Weyburn U.S. Pat. No. 812,966 discloses a caulk with a shape similar to that of the insert described herein. However, the structure and function of this caulk is different than the structure and function of the caulk of the present invention, as will be described hereinafter. The shoe of the Weyburn disclosure has no other features in common with the shoe of the present invention: PA1 Ashton U.S. Pat. No. 3,780,810 discloses a shoe which is formed by casting and annealing to avoid internal stresses which he says are common with shoes made by the standard methods. The Ashton shoe has no points in common with the shoe of the present invention, The disclosure says, in fact, that some of the features incorporated into the present invention are defects; PA1 Ovnicek U.S. Pat. No. 4,721,165 discloses a shoe which is claimed to be more scientifically designed than previous shoes. Although some of the same desirable goals are stressed as are stressed in the present invention, Ovnicek does not show the same features as herein, as will be discussed in greater detail hereinafter. The principal shortcoming of Ovnicek's horseshoe is that the natural growth of the hoof destroys the relationships disclosed and claimed therein, and thus nullifies the advantages claimed therefor. PA1 a. the insertion of a wear-resistant body of material into the shoe; or PA1 b. by the application of wear-resistant material to the surface of the shoe along that line. PA1 thereby gaining additional width on the lower surfaces for affixing thereto studs or other traction devices; PA1 providing additional space to insert therein removable threaded plugs for attaching said studs or traction devices; and PA1 providing additional support to the heel and posterior portions of the foot;
None of the references given hereinbefore discloses a shoe having a combination of features such as is disclosed and described in the present invention, or discloses all of the principal features which are considered important herein.